The purpose of this project is to study the effects of various chemicals on drug and xenobiotic metabolism in various types of cells in the lung. Of particular interest (e.g., as substrates) are those compounds, including the polycyclic aromatic hydrocarbons, which are activated by the mixed-function oxygenase system to their proximate and/or ultimate carcinogenic forms. The rat was chosen as the experimental animal because, like man, it is subject to induction of these metabolizing systems by prior exposure to certain drugs and chemicals. Factors which alter the metabolic activity of the lung may play an important role in certain environmentally caused diseases, including some types of cancer. Currently, different cell types, especially alveolar type II cells and nonciliated bronchiolar epithelial cells (Clara cells) are being isolated from rat lungs so that a detailed examination of the toxication-detoxication processes in purified cell fractions and in individual cells may be carried out. Different lung cell types appear to have different intrinsic abilities to metabolize various chemical compounds, including benzo (a) pyrene and these activities may be inducible to different extents.